To me it looks as though you are extremely close to harvest and your plant is either done and killing the fan leaves off by sucking whatever nutrients are left in them, or you are just lacking a shit ton of N.
I can't find it but there was a study where if a plant is "root bound" 3 weeks after flower it would make absolutely no difference if repotted because the plant has already grown the roots it needed to support the fruit/buds.
It wouldn't be making anymore roots thus really wouldn't be root bound.
I'd say check your feeding or trichomes but that's just me.